Dialyzer clamping means



1968 c. v. JOHNSON DIALYZER CLAMPING MEANS Filed Jan. 23, 1967 w MM 2 TN 6 6 mm 6 w 0 W W M H T 7 m //H|.\. V m a u I 3 I I 3 3 4 ,4 6 2 a n L. m w 8 ll 7 JAN \LII IP14 w H 3 BY ma? ATTORNEY United States Patent 3,397,791 DIALYZER CLAMPING MEANS Carl V. Johnson, Baldwin, N.Y., assignor to Tcchnicon Corporation, a corporation of New York Filed Jan. 23, 1967, Ser. No. 610,875 7 Claims. (Cl. 210-321) ABSTRACT OF THE DISCLOSURE A dialyzer having a pair of plates forming a flat helical, dialysis chamber, one of these plates being relatively rigid and the other of these plates being relatively flexible, and a series of clamping plates and gasket for providing pressure on the dialysis chamber plates which is uneven taken along a radius across the plates, the greatest pressure being provided over the outermost turn of the helical chamber.

BACKGROUND OF THE INVENTION (1) Field of the invention-This invention relates to apparatus for dialyzing liquids.

(2) Description of the prior art.--Dialyzers are shown in the patent to Jack Isreeli, U.S. Reissue 24,736, reissued Nov. 17, 1959. Such a dialyzer comprises a pair of plates having respective confronting surfaces into which are formed mating grooves to provide a chamber for dialysis. A semipermeable membrane is disposed between the plates, dividing the chamber into two parts, and the assembly of the two plates and the membrane is clamped together. A respective inlet and outlet are provided for each of the two parts of the chamber, so that a donor stream of liquid may be passed through one of said parts and a donee stream of liquid may be passed through the other of said parts of the chamber. In the dialyzer shown in US. Re. 24,736 the two plates are of annular shape and the chamber is a fiat helix doubled back on itself.

It is necessary that the two confronting surfaces be tightly pressed together so as to preclude leakage. Such leakage might involve liquid passage between adjacent turns of the helical chamber, and between the outermost turn and the exterior of the dialyzer. This exterior is customarily the heat transfer liquid of a heating bath. In US. Re. 24,736, this pressing together is accomplished by a pair of annular pressing plates which are sandwiched about the pair of annular dialysis chamber forming plates, and a pair of annular clamp plates which are sandwiched about the two pressing plates. This assembly of stacked plates is squeezed together by a central bolt and two nuts. Each plate in a pair is symmetrically identical to its mate. Uniform pressure over the dialysis chamber forming plates is accomplished by providing spaced apart apertures in the pressing plates to make them somewhat flexible, and providing each clamping plate with an annular rib adjacent its periphery, which rib bears against the adjacent pressing plate.

SUMMARY While the arrangement of US. Re. 24,736 has well served its purpose, it is an object of this invention to provide an improved clamping arrangement whereby to insure adequate pressure between the confronting surfaces of the dialysis chamber forming plates and thereby the preclusion of any leakage.

A feature of this invention is a dialyzer having a pair of plates forming a flat helical dialysis chamber, one of these plates being relatively thick and relatively rigid, the other of these plates being relatively thin over most of its cross-section, except for a peripheral annulus and relatively flexible; a pair of pressing plates; a pair of clamping plates; and a resiliently compressible plate dis- 3,397,791 Patented Aug. 20, 1968 ice posed between the relatively thin part of said other dialysis chamber forming plate and the adjacent pressing plate, whereby said adjacent pressing plate provides a maximum annular pressure over the outermost turn of the helical dialysis chamber, and a relatively uniform pressure over the remaining inner turns of the helix.

BRIEF DESCRIPTION OF THE DRAWING These and other objects, features and advantages of the invention will be apparent from the following specification taken in conjunction with the accompanying drawing in which:

FIG. 1 is a bottom plan view of a dialyzer embodying this invention; and

FIG. 2 is a side view in cross-section taken along the plane 22 of FIG. 1, showing the dialyzer assembled but not under clamping pressure, with certain portions rotated into the plane for illustrative purposes.

DESCRIPTION OF THE PREFERRED EMBODIMENT The semipermeable membrane 10 is disposed between a pair of annular dialysis chamber forming plates 12 and 14, which are sandwiched between a pair of annular pressing plates 16 and 18, which in turn are sandwiched between a pair of annular clamping plates 20 and 22.

The assembly of plates is held together by a central rod 24, which at one end is fixed to the clamping plate 22 by threads and a spline 26, and which at its other end is threaded to receive a clamping nut 28, and has a groove 30. The nut 28 does not directly bear against the adjacent clamping plate 20, but, rather, bears against a plurality of balls 32 which bear against a ball support member 34, which bears against the clamping plate 20. The halls are captured in opposed respective grooves 36 and 38 in the nut and the support member. A C-ring 40 captures the ball support member 34 in a recess 42 in the nut 28.

The dialysis chamber 44 is a doubled-back-on-itself, flat helical spiral, having both its inlet and its outlet at the outer periphery of the spiral and a U-shaped bend at the center of the spiral. The chamber is provided by mating grooves 46 and 48 respectively formed into the confronting faces of the plates 12 and 14. Each end of the groove terminates in a respective nipple. The groove 46 terminates in nipples 50 and 52, and the groove 48 terminates in a nipple 54 and another nipple which is not visible.

The plate 14 has a peripheral annulus 14a which is equal to the thickness of the mating plate 12, and which is made thick to accommodate the nipples, e.g., 54. The plate 14 has a central annulus 1411 which includes most of the area of the helix, which is made relatively thin, and an intermediate annulus 14c, or step, which is slightly thicker and extends at least over the outermost turn of the helix. A resiliently compressible gasket 56 is disposed between the plates 14 and 18 and rests on the step 140, and is spaced from the surface 14b by a gap 14bb and from the peripheral annulus 14a by a gap 14aa. An additional resiliently compressible gasket 58 may advantageously be disposed between the plates 12 and 16 to ensure uniform loading of the plate 12 by the plate 16. Each of the presser plates 16, 18 has an annular groove 60 to receive an annular rib 62 projecting from the respective clamping plates 20, 22. Two locating pin assemblies 64 may be provided through the plates 12 and 14.

In use the semipermeable membrane is tautly disposed between the plates 12 and 14. The nut 28 is rotated to press the member 34 against the clamp plate 20, whose rib 62 bears against the presser plate 16, which compresses the gasket 58 and bears against the plate 12, the membrane 10, the plate 14, the gasket 56, the plate 18, the rib 62 and the plate 22. Initial pressure is developed over the annular step 14c to seal the outermost turn of the helical grooves together. As clamping pressure is increased the gasket 56 is deformed to bulge outwardly into the gap 14bb to provide a substantially uniform pressure across the annulus 14b and over the remainder of the inner turns of the helix. Further, as clamping pressure is increased, the edge of the gasket 56 bulges outwardly into the gap 14am to press against the inner face of the annulus 14a in a direction perpendicular to the longitudinal axis of the rod 24 to apply a torque against the annulus 14a against, in turn, the corresponding annular portion of the plate 12. The plates 16 and 18 cannot be made with as large a diameter as the plates 12 and 14 due to the necessity of clearing the guide pin assemblies 64.

An L-shaped cover 70 may be fixed to the plate 22 by a plurality of screws 71. A flat cover 72 having a pair of hooked portions 74 adapted to fit into a pair of apertures 76 in the cover 70, and a central aperture 78 adapted to fit over the rod 24 and engage the groove 30 may be fitted onto the assembly. A pair of rising helical coils '80 may be snapped into clips 82 which are fixed to the cover 72 by suitable fasteners. These coils may have their outlets respectviely coupled to the inlets of the dialysis chamber parts, to provide for a preheating of the fluids in the heating bath before their entry into the dialysis chamber.

While a prefered embodiment of this invention has been illustrated, it will be apparent to one skilled in the art that various modifications thereto could be made without departing from the underlying principles of the invention, within the scope of the appended claims.

What is claimed is: 1. A dialyzer comprising: a pair of plate members mounted in confronting faceto-face relation; a dialyzer membrane interposed in fluid tight relation between the confronting faces of said members; each of said members having a continuous groove defined therein for providing for the flow of fluid along the adjacent surface of said member; said grooves being in registry and each having a respective inlet and outlet; clamping means for clamping said pair of plate members together comprising a pair of rigid surfaces sandwiching said plate members therebetween; the improvement wherein:

one of said plate members is made relatively thinner than the other plate member and therefore relatively flexible; and a resiliently compressible member is disposed between said one thin plate member and the adjacent rigid surface of said clamping means. 2. A dialyzer according to claim 1 wherein; said resiliently compressible member, when compressed by said clamping means, is adapted to provide a greater pressure over an outer annular portion of said one plate member than over a central annular portion. 3. A dialyzer according to claim 1 wherein; said plate members are each circular;

said one plate member has a central portion which is relatively thinner than the corresponding central portion of said other plate member, and has an outer annular portion which is thicker than said thinner central portion.

4. A dialyzer according to claim 1 wherein;

said continuous grooves are disposed in a flat helix having at least the outermost turn thereof disposed within outer annular portion.

5. A dialyzer according to claim 1 wherein;

said plate members are each circular;

said one plate member has a central portion which is relatively thinner than the corresponding .central portion of said other plate member, an outermost annular portion which is substantially of equal thickness to the corresponding outermost annular portion of said other plate member, and an intermediate annular portion which is thicker than said central portion and thinner than said outermost portion;

said grooves being formed in a fiat, doubled-back-onitself helix, with at least the outermost turn thereof being in registry with said intermediate annular portion and the remaining inner turns thereof being in registry with said central portion.

6. A dialyzer according to claim 5 wherein;

said resiliently compressible member is a circular flat disk having one face. disposed on said intermediate annular portion of said one plate member, and before longitudinal clamping pressure is applied, said one face is longitudinally spaced from said central portion of said one plate member, its edge is radially spaced from the inner confronting edge of said outermost portion of said one plate member, and its other face is disposed above the adjacent face of said outermost portion to space said adjacent rigid surface of said clamping means from said adjacent face of said outermost portion of said one plate member.

7. A dialyzer according to claim 6 wherein;

said rigid surface of said clamping means is fiat, and

upon the application of clamping pressure, said resiliently compressible member develops maximum pressure in registry with said outer annular portion of said one plate member, bulges longitudinally into pressure developing abutment with said central portion of said one plate member, and bulges radially into pressure developing abutment with said inner confronting edge of said outermost portion of said one plate member.

References Cited UNITED STATES PATENTS 11/1959 Isreeli 2l0321 8/1967 Isreeli 2l032l 

